Mr McDonnell told the Guardian: “The alarming increase in average household debt already means many families in our country are struggling over the Christmas period.

“The Tories have gripping our country and have no solutions to offer those struggling to get by as prices run ahead of wages.

He added: “The next Labour government will introduce a £10 per hour real living wage, scrap student fees, end the public sector pay cap and cap interest on consumer credit to build an economy for the many, not the few.”

The figures produced by Labour are based on official statistics - which show the total amount of unsecured debt in Britain was £392.8bn in the third quarter of this year - and government forecasts.